Machine Guarding Ppt

1. OSHA Office of Training and Education 1
MachineMachine Guarding Guarding

2. OSHA Office of Training and Education 2
IntroductionIntroduction
Crushed hands and arms, severed fingers, blindness -
the list of possible machinery-related injuries is as long
as it is horrifying. Safeguards are essential for protecting
workers from needless and preventable injuries.
A good rule to remember is: Any machine part, function,
or process which may cause injury must be safeguarded.
Where the operation of a machine can injure the
operator or other workers, the hazard must be controlled
or eliminated.

3. OSHA Office of Training and Education 3
Causes of Machine AccidentsCauses of Machine Accidents
Reaching in to “clear” equipment
Not using Lockout/Tagout
Unauthorized persons doing maintenance or
using the machines
Missing or loose machine guards

4. OSHA Office of Training and Education 4
Where Mechanical Hazards OccurWhere Mechanical Hazards Occur
Point of operation
All parts of the machine which move, such as:
flywheels, pulleys, belts, couplings, chains,
cranks, gears, etc.
tfeed mechanisms and auxiliary parts of the
machine
In-running nip points

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Point of OperationPoint of Operation
That point where work is performed on the
material, such as cutting, shaping, boring,
or forming of stock must be guarded.

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Rotating PartsRotating Parts

7. OSHA Office of Training and Education 7
In-Running Nip PointsIn-Running Nip Points
Belt and
pulley
Chain and
sprocket
Rack and
pinion
Rotating
cylinders

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Requirements for SafeguardsRequirements for Safeguards
Prevent contact - prevent worker’s body or clothing from
contacting hazardous moving parts
Secure - firmly secured to machine and not easily
removed
Protect from falling objects - ensure that no objects can
fall into moving parts
Create no new hazards - must not have shear points,
jagged edges or unfinished surfaces
Create no interference - must not prevent worker from
performing the job quickly and comfortably
Allow safe lubrication - if possible, be able to lubricate the
machine without removing the safeguards

9. OSHA Office of Training and Education 9
Methods of Machine SafeguardingMethods of Machine Safeguarding
Guards
Sfixed
Sinterlocked
Sadjustable
Sself-adjusting
Devices
Spresence sensing
Spullback
Srestraint
Ssafety controls (tripwire
cable, two-hand contol, etc.)
cgates
Location/distance
Feeding and ejection methods
tautomatic and/or semi-
automatic feed and
ejection
nrobots
Miscellaneous aids
dawareness barriers
rprotective shields
dhand-feeding tools

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Fixed GuardFixed Guard
Provides a barrier - a permanent part of the
machine, preferable to all other types of guards.

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Interlocked GuardInterlocked Guard
When this type of guard is opened or removed, the
tripping mechanism and/or power automatically
shuts off or disengages, and the machine cannot
cycle or be started until the guard is back in place.
Interlocked
guard on
revolving drum

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Adjustable GuardAdjustable Guard
Provides a barrier which may be adjusted to
facilitate a variety of production operations.
Bandsaw blade
adjustable guard

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Self-Adjusting GuardSelf-Adjusting Guard
Provides a barrier which moves according to
the size of the stock entering the danger area.
Circular table saw
self-adjusting guard

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Pullback DevicePullback Device
Utilizes a series of cables
attached to the operator’s
hands, wrists, and/or arms
Primarily used on machines
with stroking action
Allows access to the point of
operation when the
slide/ram is up
Withdraws hands when the
slide/ram begins to descend

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Pullback Device Pullback Device (cont’d)(cont’d)
Hands in die, feeding
Point of operation exposed
Pullback device attached
and properly adjusted
Die closed
Hands withdrawn from point
of operation by pullback
device

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Restraint DeviceRestraint Device
Uses cables or straps
attached to the operator’s
hands and a fixed point
Must be adjusted to let the
operator’s hands travel
within a predetermined
safe area
Hand-feeding tools are often
necessary if the operation
involves placing material
into the danger area

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Safety Tripwire CablesSafety Tripwire Cables
Device located around
the perimeter of or
near the danger area
Operator must be able to
reach the cable to
stop the machine

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Two-Hand ControlTwo-Hand Control
Requires constant,
concurrent pressure to
activate the machine
The operator’s hands are
required to be at a safe
location (on control
buttons) and at a safe
distance from the danger
area while the machine
completes its closing cycle

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GateGate
Movable barrier device which protects the operator at the
point of operation before the machine cycle can be
started
If the gate does not fully close, machine will not function
Gate Open Gate Closed

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Safeguarding by Safeguarding by
Location/DistanceLocation/Distance
Locate the machine or its
dangerous moving parts
so that they are not
accessible or do not
present a hazard to a
worker during normal
operation
Maintain a safe distance
from the danger area

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Automatic FeedAutomatic Feed
(shown on power press)(shown on power press)
Transparent
Enclosure
Guard
Stock Feed
Roll
Danger
Area
Completed Work

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RobotsRobots
Machines that load and
unload stock, assemble
parts, transfer objects,
or perform other tasks
Best used in high-
production processes
requiring repeated
routines where they
prevent other hazards
to employees

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Protective ShieldsProtective Shields
These do not give complete protection from machine
hazards, but do provide some protection from flying
particles, splashing cutting oils, or coolants.

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Holding ToolsHolding Tools
Used to place and remove
stock in the danger area
Not to be used instead of
other machine safeguards,
but as a supplement

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Some Examples of OSHA Machine Some Examples of OSHA Machine
Guarding Requirements . . . .Guarding Requirements . . . .

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Guarding Fan BladesGuarding Fan Blades
When the periphery of the blades of a fan is less
than 7 feet above the floor or working level, the
blades must be guarded with a guard having
openings no larger than 1/2 inch.

27. OSHA Office of Training and Education 27
Abrasive Wheel MachineryAbrasive Wheel Machinery
Work rests on offhand grinding machines must be kept
adjusted closely to the wheel with a maximum opening
of 1/8-inch to prevent the work from being jammed
between the wheel and the rest, which may result in
wheel breakage.

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Abrasive Wheel MachineryAbrasive Wheel Machinery
The distance between the wheel periphery and the
adjustable tongue must never exceed 1/4-inch.

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Power-Transmission ApparatusPower-Transmission Apparatus
Power-transmission
apparatus (shafting,
flywheels, pulleys, belts,
chain drives, etc.) less
than 7 feet from the floor
or working platform must
be guarded.
Unguarded belt
and pulley

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Machine Safety ResponsibilitiesMachine Safety Responsibilities
Management
Sensure all machinery is properly guarded
Supervisors
Strain employees on specific guard rules in their areas
oensure machine guards remain in place and are
functional
uimmediately correct machine guard deficiencies
Employees
Sdo not remove guards unless machine is locked and
tagged
areport machine guard problems to supervisors
immediately
udo not operate equipment unless guards are in place

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Training Training
Hazards associated with particular machines
How the safeguards provide protection and the hazards
for which they are intended
How and why to use the safeguards
How and when safeguards can be removed and by
whom
What to do if a safeguard is damaged, missing, or
unable to provide adequate protection
Operators should receive training on the following:

32. OSHA Office of Training and Education 32
SummarySummary
Safeguards are essential for protecting workers
from needless and preventable machinery-
related injuries
The point of operation, as well as all parts of the
machine that move while the machine is
working, must be safeguarded
A good rule to remember is: Any machine part,
function, or process which may cause injury
must be safeguarded